操作系统实验内存分配

1、 西 安 邮 电 大 学 （计算机学院）课内实验报告实验名称： 内存管理 专业名称： 软件工程班 级： 学生姓名： 学号（8位）：指导教师： 实验日期： 实验五：进程1.实验目的 通过深入理解区管理的三种算法，定义相应的数据结构，编写具体代码。 充分模拟三种算法的实现过程，并通过对比，分析三种算法的优劣。（1）掌握内存分配FF，BF，WF策略及实现的思路；（2）掌握内存回收过程及实现思路；（3）参考给出的代码思路，实现内存的申请、释放的管理程序，调试运行，总结程序设计中出现的问题并找出原因，写出实验报告。2.实验要求：1） 掌握内存分配FF，BF，WF策略及实现的思路；2） 掌握内存回收过程及

2、实现思路；3） 参考本程序思路，实现内存的申请、释放的管理程序，调试运行，总结程序设计中出现的问题并找出原因，写出实验报告。3. 实验过程：创建进程：删除其中几个进程：(默认以ff首次适应算法方式排列)Bf 最佳适应算法排列方式：wf最差匹配算法排列方式：4. 实验心得： 这次实验实验时间比较长，而且实验指导书中对内存的管理讲的很详细，老师上课的时候也有讲的很详细，但是代码比较长，刚开始的时候也是不太懂，但是后面经过和同学一起商讨，明白几种算法的含义： 首次适应算法。在采用空闲分区链作为数据结构时，该算法要求空闲分区链表以地址递增的次序链接。在进行内存分配时，从链首开始顺序查找，直至找到一个能

3、满足进程大小要求的空闲分区为止。然后，再按照进程请求内存的大小，从该分区中划出一块内存空间分配给请求进程，余下的空闲分区仍留在空闲链中。 循环首次适应算法。该算法是由首次适应算法演变而形成的，在为进程分配内存空间时，从上次找到的空闲分区的下一个空闲分区开始查找，直至找到第一个能满足要求的空闲分区，并从中划出一块与请求的大小相等的内存空间分配给进程。 最佳适应算法将空闲分区链表按分区大小由小到大排序，在链表中查找第一个满足要求的分区。 最差匹配算法将空闲分区链表按分区大小由大到小排序，在链表中找到第一个满足要求的空闲分区。实验中没有用到循环首次适应算法，但是对其他三种的描述还是很详细，总的来说，

4、从实验中还是学到了很多。5.程序源代码：#include<stdio.h>#include<malloc.h>#include<unistd.h>#include<stdlib.h>#define PROCESS_NAME_LEN 32 /进程名长度#define MIN_SLICE 10 /最小碎片的大小#define DEFAULT_MEM_SIZE 1024/内存大小#define DEFAULT_MEM_START 0 /起始位置/*内存分配算法*/#define MA_FF 1#define MA_BF 2#define MA_WF 3

5、/*描述每一个空闲块的数据结构*/struct free_block_typeint size;/空闲块大小int start_addr;/空闲块起始地址struct free_block_type *next;/指向下一个空闲块;/*指向内存中空闲块链表的首指针*/struct free_block_type *free_block = NULL;/*每个进程分配到的内存块的描述*/struct allocated_blockint pid;/进程标识符int size;/进程大小int start_addr;/进程分配到的内存块的起始地址char process_namePROCESS_N

6、AME_LEN;/进程名struct allocated_block *next;/指向下一个进程控制块;/*进程分配内存块链表的首指针*/struct allocated_block *allocated_block_head = NULL;int free_block_count = 0;/空闲块个数int mem_size = DEFAULT_MEM_SIZE; /内存大小int current_free_mem_size = 0;/当前空闲内存大小int ma_algorithm = MA_FF; /当前分配算法static int pid = 0; /初始PIDint flag =

7、0;/设置内存大小标志,表示内存大小是否设置/*函数声明*/struct free_block_type* init_free_block(int mem_size);void display_menu();int set_mem_size();void set_algorithm();void rearrange(int algorithm);int rearrange_WF();int rearrange_BF();int rearrange_FF();int new_process();int allocate_mem(struct allocated_block *ab);void k

8、ill_process();int free_mem(struct allocated_block *ab);int dispose(struct allocated_block *free_ab);int display_mem_usage();struct allocated_block *find_process(int pid);int do_exit();int allocate_FF(struct allocated_block *ab);int allocate_BF(struct allocated_block *ab);int allocate_WF(struct alloc

9、ated_block *ab);int allocate(struct free_block_type *pre, struct free_block_type *allocate_free_nlock, struct allocated_block *ab);int mem_retrench(struct allocated_block *ab);/ 通过内存紧缩技术给新进程分配内存空间int mem_retrench(struct allocated_block *ab)struct allocated_block *allocated_work, *allocated_pre = all

10、ocated_block_head;struct free_block_type *free_work, *free_pre = free_block->next;if(allocated_pre = NULL)return -1;allocated_pre->start_addr = 0;allocated_work = allocated_pre->next;while(allocated_work != NULL)allocated_work->start_addr = allocated_pre->start_addr + allocated_pre-&g

11、t;size;allocated_pre = allocated_work;allocated_work = allocated_work->next;free_block->start_addr = allocated_pre->start_addr + allocated_pre->size;free_block->size = current_free_mem_size;free_block->next = NULL;free_work = free_pre;while(free_pre != NULL)free(free_pre);free_pre

12、= free_work;if(free_pre != NULL)free_work = free_work->next;allocate(NULL, free_block, ab);return 1;/ 给新进程分配内存空间 int allocate(struct free_block_type *pre, struct free_block_type *allocate_free_block, struct allocated_block *ab)struct allocated_block *p = allocated_block_head;ab->start_addr = a

13、llocate_free_block->start_addr;if(allocate_free_block->size - ab->size < MIN_SLICE)ab->size = allocate_free_block->size;if(pre != NULL)pre->next = allocate_free_block;elsefree_block = allocate_free_block->next;free(allocate_free_block);elseallocate_free_block->start_addr +

14、= ab->size;allocate_free_block->size -= ab->size;if(p = NULL)allocated_block_head = ab;elsewhile(p->next != NULL)p = p->next;p->next = ab;current_free_mem_size -= ab->size;if(current_free_mem_size = 0)free_block = NULL;return 0;/按照最坏适应算法给新进程分配内存空间int allocate_WF(struct allocated

15、_block *ab)int ret;struct free_block_type *wf = free_block;if(wf = NULL)return -1;if(wf->size >= ab->size)allocate(NULL, wf, ab);else if(current_free_mem_size >= ab->size)ret = mem_retrench(ab);elseret = -2;rearrange_WF();return ret;/ 按照最佳适应算法给新进程分配内存空间int allocate_BF(struct allocated

16、_block *ab)int ret;struct free_block_type *pre = NULL, *bf = free_block;if(bf = NULL)return -1;while(bf != NULL)if(bf->size >= ab->size)ret = allocate(pre, bf,ab);break;pre = bf;pre = pre->next;if(bf = NULL && current_free_mem_size > ab->size)ret = mem_retrench(ab);elseret

17、= -2;rearrange_BF();return ret;/ 按照首次适应算法给新进程分配内存空间int allocate_FF(struct allocated_block *ab)int ret;struct free_block_type *pre = NULL, *ff = free_block;if(ff = NULL)return -1;while(ff != NULL)if(ff->size >= ab->size)ret = allocate(pre, ff,ab);break;pre = ff;pre = pre->next;if(ff = NUL

18、L && current_free_mem_size > ab->size)ret = mem_retrench(ab);elseret = -2;rearrange_FF();return ret;/分配内存模块int allocate_mem(struct allocated_block *ab)int ret ;struct free_block_type *fbt, *pre;int request_size = ab->size;fbt = pre = free_block;switch(ma_algorithm)case MA_FF :ret =

19、allocate_FF(ab);break;case MA_BF :ret = allocate_BF(ab);break;case MA_WF :ret = allocate_WF(ab);break;default :break;return ret;/ 创建一个新的进程。int new_process()struct allocated_block *ab;int size;int ret;ab = (struct allocated_block *)malloc(sizeof(struct allocated_block);if(!ab)exit(-5);ab->next = N

20、ULL;pid+;sprintf(ab->process_name, "PROCESS-%02d", pid);/sprintf()函数将格式化的数据写入某字符串中ab->pid = pid; printf("Memory for %s:", ab->process_name);for(; ; )scanf("%d", &size);getchar();if(size > 0)ab->size = size;break;elseprintf("The size have to great

21、er than zero! Please input again!");ret = allocate_mem(ab); /从空闲区分配内存，ret=1表示分配okif(ret = 1) && (allocated_block_head = NULL)/如果此时allocated_block_head尚未赋值，则赋值 /进程分配链表为空allocated_block_head = ab;return 1;else if(ret = 1) /分配成功，将该已分配块的描述插入已分配链表ab->next = allocated_block_head;/头插法alloca

22、ted_block_head = ab;return 2;else if(ret = -1) /分配不成功printf("Allocation failn");free(ab);return -1; return 3;/退出程序并释放内存空间。int do_exit()struct allocated_block *allocated_ab, *allocated_pre;struct free_block_type *free_ab, *free_pre;free_pre = free_block;allocated_pre = allocated_block_head;

23、if(free_pre != NULL)free_ab = free_pre->next;while(free_ab != NULL)free(free_pre);free_pre = free_ab;free_ab = free_ab->next;if(allocated_pre != NULL)allocated_ab = allocated_pre->next;while(allocated_ab != NULL)free(allocated_pre);allocated_pre = allocated_ab;allocated_ab = allocated_ab-&g

24、t;next;allocated_ab = allocated_ab->next;return 0;/在进程分配链表中寻找指定进程。struct allocated_block *find_process(int pid)struct allocated_block *ab = allocated_block_head;if(ab = NULL)printf("Here?111111111n");return NULL;while(ab->pid != pid && ab->next != NULL)ab = ab->next;if(

25、ab->next = NULL && ab->pid != pid)printf("Here?2222222n");return NULL;return ab;/显示当前内存的使用情况，包括空闲区的情况和已经分配的情况。int display_mem_usage()struct free_block_type *fbt = free_block;struct allocated_block *ab = allocated_block_head;printf("-n");/显示空闲区printf("Free Memor

26、y:n");printf("%20s %20sn", " start_addr", " size");while(fbt != NULL)printf("%20d %20dn", fbt->start_addr, fbt->size);fbt = fbt->next;/显示已分配区printf("nUsed Memory:n");printf("%10s %20s %10s %10sn", "PID", "Proces

27、sName", "start_addr", " size");while(ab != NULL)printf("%10d %20s %10d %10dn", ab->pid, ab->process_name, ab->start_addr, ab->size);ab = ab->next;printf("-n");return 1;/ 释放ab数据结构节点。int dispose(struct allocated_block *free_ab)struct allocate

28、d_block *pre, *ab;if(free_block = NULL)return -1;if(free_ab = allocated_block_head)/如果要释放第一个节点allocated_block_head = allocated_block_head->next;free(free_ab); elsepre = allocated_block_head; ab = allocated_block_head->next;/找到free_abwhile(ab != free_ab)pre = ab;ab = ab->next;pre->next =

29、ab->next;free(ab);return 1;/*将ab所表示的已分配区归还，并进行可能的合并*/int free_mem(struct allocated_block *ab)int algorithm = ma_algorithm;struct free_block_type *fbt, *pre, *work;fbt = (struct free_block_type*)malloc(sizeof(struct free_block_type);if(!fbt)return -1;pre = free_block;fbt->start_addr = ab->st

30、art_addr;fbt->size = ab->size;fbt->next = NULL;if(pre != NULL)while(pre->next != NULL)pre = pre->next;pre->next = fbt;elsefree_block = fbt;rearrange_FF();pre = free_block;work = pre->next;while(work != NULL)if(pre->start_addr + pre->size = work->start_addr)pre->size

31、+= work->size;free(work);work = pre->next;elsepre = work;work = work->next;current_free_mem_size += ab->size;return 1;/ 删除进程，归还分配的存储空间，并删除描述该进程内存分配的节点。void kill_process()struct allocated_block *ab;int pid;printf("Kill Process, pid=");scanf("%d", &pid);getchar();ab

32、 = find_process(pid);if(ab != NULL)free_mem(ab); /*释放ab所表示的分配区*/dispose(ab); /*释放ab数据结构节点*/按FF算法重新整理内存空闲块链表,按空闲块首地址排序。int rearrange_FF()struct free_block_type *head = free_block;struct free_block_type *forehand, *pre, *rear;int i;if(head = NULL)return -1;/冒泡排序for(i = 0; i < free_block_count-1; i+

33、)forehand = head;pre = forehand->next;rear = pre->next;while(pre->next != NULL)if(forehand = head && forehand->start_addr >= pre->start_addr)/比较空闲链表中第一个空闲块与第二个空闲块的开始地址的大小head->next = pre->next;pre->next = head;head = pre;forehand = head->next;pre = forehand->

34、next;rear = pre->next;else if(pre->start_addr >= rear->start_addr)/比较链表中其他相邻两节点的开始地址的大小pre->next = rear->next;forehand->next = rear;rear->next = pre;forehand = rear;rear = pre->next;elseforehand = pre;pre = rear;rear = rear->next;return 0;/ 按BF算法重新整理内存空闲块链表,按空闲块大小从小到大排序

35、。int rearrange_BF()struct free_block_type *head = free_block;struct free_block_type *forehand, *pre, *rear;int i;if(head = NULL)return -1;/冒泡排序for(i = 0; i < free_block_count-1; i+)forehand = head;pre = forehand->next;rear = pre->next;while(pre->next != NULL)if(forehand = head &&

36、 forehand->size <= pre->size)/比较空闲链表中第一个空闲块与第二个空闲块的空间的大小head->next = pre->next;pre->next = head;head = pre;forehand = head->next;pre = forehand->next;rear = pre->next;else if(pre->size <= rear->size)/比较链表中其他相邻两节点的空间的大小pre->next = rear->next;forehand->next

37、 = rear;rear->next = pre;forehand = rear;rear = pre->next;elseforehand = pre;pre = rear;rear = rear->next;return 0;/按WF算法重新整理内存空闲块链表,按空闲块大小从大到小排序。int rearrange_WF()struct free_block_type *head = free_block;struct free_block_type *forehand, *pre, *rear;int i;if(head = NULL)return -1;/冒泡排序for

38、(i = 0; i < free_block_count-1; i+)forehand = head;pre = forehand->next;rear = pre->next;while(pre->next != NULL)if(forehand = head && forehand->size >= pre->size)/比较空闲链表中第一个空闲块与第二个空闲块空间的大小head->next = pre->next;pre->next = head;head = pre;forehand = head->ne

39、xt;pre = forehand->next;rear = pre->next;else if(pre->size >= rear->size)/比较链表中其他相邻两节点的空间的大小pre->next = rear->next;forehand->next = rear;rear->next = pre;forehand = rear;rear = pre->next;elseforehand = pre;pre = rear;rear = rear->next;return 0;/按指定的算法整理内存空闲块链表。void r

40、earrange(int algorithm)switch(algorithm)case MA_FF:rearrange_FF();break;case MA_BF:rearrange_BF();break;case MA_WF:rearrange_WF();break;/设置当前的分配算法void set_algorithm()int algorithm;/system("clear");printf("t1 - First Fitn");/首次适应算法printf("t2 - Best Fit n");/最佳适应算法printf(

41、"t3 - Worst Fit n");/最坏适应算法printf("nPlease choose(13):");for(; ; )scanf("%d", &algorithm);getchar();if(algorithm >= 1 && algorithm <= 3) ma_algorithm = algorithm;break;elseprintf("nCannot input %d, Please input 13 : ", algorithm);/按指定算法重新排列空闲

42、区链表 rearrange(ma_algorithm); /设置内存的大小int set_mem_size()int size;if(flag != 0)/防止重复设置 printf("Cannot set memory size againn"); return 0; printf("Total memory size = ");for(; ; )scanf("%d", &size);getchar();if(size > 0)current_free_mem_size = size;mem_size = size;/设置内存大小为sizefree_bloc